import turtle, random

pen = turtle.Pen()
pen.speed(10)

colors = ['black', 'red', 'yellow', 'blue', 'green']

for i in range(20):
    pen.penup()
    pen.goto(0, -10 * i)
    pen.pendown()
    pen.color(random.choice(colors))
    pen.circle(i * 10 + 15)

turtle.done()
